On Thursday, 15 May 2014 08:45:47 UTC+1, Jeroen Demeyer wrote: > > On 2014-05-15 01:06, Dima Pasechnik wrote: > > On 2014-05-14, Volker Braun <[email protected] <javascript:>> wrote: > >> Instead of projecting (which requires some convention about bases to be > >> able to work with coordinates) I would try to use the Minkowski sum > with > >> the linear space in the direction that you want to unconstrain. > > > > IMHO, Jeroen needs to use Fourier-Motzkin elimination. > Yes, something like that. Elimination based purely on the H-rep without > first computing the V-rep. Is this implemented in Sage? In PPL? >
AFAIK PPL does not have it implemented, they rely on V-representations to compute projections. On the other hand Fourier-Motzkin elimination is behind at least one method to go from H- to V-representations. (implemented in cdd, and perhaps in PPL too?) lrs, a package of Sage, implements a rather different method of finding V-representations, which is sometimes more efficient (and it is not as memory-hungry as Fourier-Motzkin). HTH, Dima -- You received this message because you are subscribed to the Google Groups "sage-support" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at http://groups.google.com/group/sage-support. For more options, visit https://groups.google.com/d/optout.
